Method and device for determining the state of travel of a vehicle

• US 20060132356A1
• Filed: 12/05/2005
• Published: 06/22/2006
• Est. Priority Date: 12/10/2004
• Status: Active Grant

• Current Assignee: Continental Automotive France (Continental AG)
• Original Assignee: Continental Automotive France (Continental AG)
• Inventors: Dulac, Gilles
• Granted Patent: US 7,432,851 B2
• Time in Patent Office: Days
• US Class Current: 342/173
• CPC Class Codes: B60C 23/0416 allocating a corresponding wheel position on vehicle, e.g. front/left or rear/right

Abstract

A method and a device for determining the state of travel, whether stationary or moving along, of a vehicle. The method includes equipping at least one wheel (2) with a magnetic sensor (4) having an axis of maximum sensitivity, measuring a signal at the terminals of the magnetic sensor (4) so as to deliver a signal representative of the variations in the values of the magnetic field as detected by the magnetic sensor, and in providing either information that the vehicle is stationary if there are no variations in the signal delivered, or information that the vehicle is moving along when there is a cyclic variation in the signal.

Claims

1. A method for determining the state of travel, whether stationary or moving along, of a vehicle (3), characterized in that it consists in equipping at least one of the wheels (2) of said vehicle with a magnetic sensor (4;

4′

) having an axis of maximum sensitivity (S4), and;

in measuring a signal at the terminals of the magnetic sensor (4;

4′

) so as to deliver a signal representative of the variations in the values of the magnetic field as detected by said magnetic sensor,

and in providing either information that the vehicle is stationary if there are no variations in the signal delivered, or information that the vehicle is moving along when there is a cyclic variation in said signal.

2. The method as claimed in claim 1, characterized in that, when the vehicle (3) is moving, the period of the cyclic signal representative of the variations in the values of the magnetic field which are detected via the magnetic sensor (4;

4′

) is measured and this data item is used to calculate the rotational speed of the wheel (2) equipped with said magnetic sensor.

3. The method as claimed in claim 1 intended for a vehicle (3) provided with wheels (2) which are equipped with an electronic unit (1) for monitoring and/or measuring a parameter, incorporating a low-frequency antenna (4) consisting of an inductor, characterized in that the information regarding the state of travel of the vehicle (3) is delivered on the basis of measurements of the signal at the terminals of said antenna-forming inductor.

4. The method as claimed in claim 1 characterized in that:

the wheel (2) is equipped with a second magnetic sensor (5′

), said second magnetic sensor and the first magnetic sensor (4′

) being positioned in such a way that their axes of maximum sensitivity (S4, S5) lie in a plane that is secant to the axis of rotation (R) of the wheel (2) and are offset from one another, in this secant plane, by a predetermined angle θ

,

and, as the vehicle moves in a given direction of travel;

the signal generated by the variation in the magnetic field is measured at the terminals of each of the two magnetic sensors (4′

, 5′

) so as to deliver two periodic signals phase-shifted with respect to one another by an angular value equal to (+ or −

) θ

, each one representative of the variations in the values of the magnetic field as detected by said magnetic sensors during one revolution of the wheel (2),

this phase shift is used to determine the direction of rotation of the wheel (2),

and from this direction of rotation and from the direction of travel of the vehicle (3), the location of the wheel (2), whether positioned on the right or on the left, is deduced.

5. The method as claimed in claim 4, characterized in that the two magnetic sensors (4′

, 5′

) are positioned in such a way that their axes of maximum sensitivity (S4, S5) lie orthogonal to one another, in a plane orthogonal to the axis of rotation (R) of the wheel (2).

6. The method as claimed in claim 4 characterized in that the state of travel of the vehicle (3) is determined by alternately measuring, during predetermined periods of time, the signal at the terminals either of the first magnetic sensor (4′

) or of the second magnetic sensor (5′

).

7. The method as claimed in claim 1, characterized in that the vehicle (3) is equipped with a magnet (10) that is fixed with respect to each wheel (2) equipped with at least one magnetic sensor (4;

4′

, 5′

), said magnet being positioned and having a power suitable for generating a magnetic field covering a zone through which said magnetic sensor passes as said wheel rotates.

8. A device for determining the state of travel, whether stationary or moving along, of a vehicle (3), characterized in that it comprises, mounted on at least one of the wheels (2) of said vehicle:

a magnetic sensor (4;

4′

) having an axis of maximum sensitivity (S4),

means (6, 7) for measuring a signal at the terminals of the magnetic sensor (4), these means being able to deliver a signal representative of the variations in the values of the magnetic field as detected by said magnetic sensor,

and a calculation unit (8) programmed to provide information that the vehicle is stationary if there are no variations in the signal delivered by the measurement means (6, 7), and information that the vehicle is moving along when there is a cyclic variation in said signal.

9. The device as claimed in claim 8, characterized in that the calculation unit (8) is programmed, as the vehicle (3) moves along, to measure the period of the cyclic signal delivered by the measurement means (6, 7) and to calculate, from this data item, the rotational speed of the wheel (2) equipped with the magnetic sensor (4;

4′

).

10. The device as claimed in claim 8, intended for vehicles (3) provided with wheels (2) which are equipped with an electronic unit (1) for monitoring and/or measuring a parameter, incorporating a low-frequency antenna (4) consisting of an inductor, characterized in that the measurement means (6, 7) are arranged in such a way as to measure a signal at the terminals of said antenna-forming inductor.

11. The device as claimed in claim 8, characterized in that:

it comprises, mounted on the wheel (2), a second magnetic sensor (5′

), said second magnetic sensor and the first magnetic sensor (4′

) being positioned in such a way that their axes of maximum sensitivity (S4, S5) lie in a plane that is secant to the axis of rotation (R) of the wheel (2) and are offset from one another, in this secant plane, by a predetermined angle θ

,

the measurement means (6, 7) are arranged at the terminals of each of the two magnetic sensors (4′

, 5′

) so as to deliver, as the vehicle (3) moves along, two periodic signals phase-shifted with respect to one another by an angular value equal to (+ or −

) θ

, each one representative of variations in the values of the magnetic field as detected by said magnetic sensors during one revolution of the wheel (2),

and the calculation unit (8) is programmed to determine, from the phase shift between the two periodic signals, the direction of rotation of the wheel (2) and, from this direction of rotation and from the direction of travel of the vehicle (3), to deduce the position, on the right or on the left, of the wheel (2).

12. The device as claimed in claim 11, characterized in that the two magnetic sensors (4′

, 5′

) are positioned in such a way that their axes of maximum sensitivity (S4, S5) lie orthogonal to one another, in a plane orthogonal to the axis of rotation of the wheel (2).

13. The device as claimed in claim 8, characterized in that it comprises a magnet (10) mounted fixedly on the vehicle (3) with respect to each wheel (2) equipped with at least one magnetic sensor (4;

4′

, 5′

), said magnet being positioned and having a power suitable for generating a magnetic field covering a zone through which said magnetic sensor passes as said wheel rotates.